Photographic film of the monopack type adapted for color photography



Patented Feb. 18, 1936 PATENT "OFFICE 2,030,904 PHOTOGRAPHIC FILM OF THE MONOPACK TYPE ADAPTED I RAPHY FOR COLOR- PHOTOG- Hans von Fraunhofer, New York, N. Y.,

to Omnichrome Corporation, New York, N. Y a,corporation of New York Serial No. 738,299

No Drawing. Application August 3, 193,

11 Claims.

This invention relates to improvements in photographic films of the mono-pack type adapted for color photography, being particularly directed to sensitized multi-strata films and methods of producing the same.

Up to the present time, considerable diificulty has been encountered in the production of films for color photography, due to the following factors: bi-packs and tri-packs, the separate sections of which are sensitized for difierent colors, have the mechanical difficulty presented by the necessity for taking two or three exposures simultaneously, plus the inherent difiiculty in volved in attempting to align difierent images and color values of the different supports for transposition on a single finished print.

Further, in passing light through oneor more carriers in preparation of the final print, there is such a loss due to difiusion, that a clear, balanced 20 and incorporated image and the full color and line values of the subject being photographed are layers or strata to form the mono-pack are super-i imposed one on top of the other with respect to the carrier, or disposed on opposite sides thereof, and alternate methods are used for producing the sensitized film, as, for example (a) each layer is 3 sensitized for its color value after it has been disposed on its carrier; (1)) an emulsion is sensitized for color and then spread upon the carrier on opposite sides thereof or one on top of the other, or (c) a layer of emulsion on a carrier is 40 subjected successively to sensitizers for warmer V and colder colors or vice versa, with the result that two layers are formed; in the first of the mono-pack methods diificulty is involved in the intermixture in a plurality of layers or the in- 45 complete distribution in respective layers of the color sensitizing dyes. In the last of such monopack methods, there is indicatedan ever-present problem in the nature of improper, incomplete and unbalanced diffusion of the sensitizing dyes into the emulsion on the carrier, with the result that the necessary strata formation for images of respective color values approximating th natural, has not to date been produced.

Broadly, it is an object of this invention to provide for a novel formof multi-strata mono-pack film and a simple and efiicient method of probeing so constituted with respect to the silver I to analysis for the production of images approxiducing the same, involving the application of a sensitizing solution containing sensitizing and filter dyes of color value capable of difiusing into the emulsion in a single step operation to provide the sensitized multi-strataformation necessary to produce images in natural color.

, Still further, it is an object of this invention to provide a method of applying a series of sensitizers in a single solution to an emulsion, such sensitizers incorporating dyes in solution, respective particles of which are of different size, whereby the sensitizing solution, that is, the respective sensitizing and filter dyes thereof, are difiused into the emulsion to produce a plurality of strata, each sensitized for a different color value, the coniponentsof the sensitizing solution being such for the respective color values as-to provide a different rate of difiusion of the dyes imparting the particular color values to the. silver salts in the emulsion and color absorption within the emulsion within only certain defined depths or strata; the sentizi ng solution being preferably so constituted as'to provide for red sensitization at the uppermost or emergent'strata, green sensitization for the middle 'or intermediate strata and blue sensitization for the lowermost or entrance strata. Although the order and arrangeme'nt of strata may be reversed by difference in method of application of the sensitizing solution to the emulsion or by difference in particle size and constitution of the respective dyes in such solution. I Specifically, it is an object of this invention to. apply to an emulsion a solution comprisinga mixture of sensitizing dyes and filter dyes of such composition and so constituted'to particle size as to yield upon treatment of a common single. layered photographic film, a three-layered stratification oi the emulsion of such film, each stratum salt-dye reaction product formed in the stratum as to permit only the .reaction, from the standpoint of subtractive analysis, of the silver saltdye reaction product, with the light of a specific color in each such specific stratum, so that upon treatment of a single layer film with such sensitizing solution, the layen is acted upon -to form three strata, each of which is efiectively sensitized mating the natural coloration according to the demands of three color photography.

In general, therefore, this invention contemplates the treatment of a monoapack film by incorporating in the emulsion thereof in a single operation, dyes for both color sensitization and in the particular instance, a three-layer strati-- fication of the film emulsion, the silver salt in the respective strata and the strata being sensitized and afiected as to provide acceptance by analysis of the primary color components of light so as to produce upon exposure of the film, images v incorporating the respective primary colors, in the different strata, and their derivatives, substantially reproducing natural coloration with full clarity and depth. It is to be understood that three-layer stratification and color sensitization thereof, as herein practiced, to produce three-color photography, in-

volves a process of incorporatingcolor dyes in the form of color sensitizers to produce sensitization respectively for the wa colors incorporating red and yellow, but pre onderantly red, and colder colors incorporating green and blue. but preponderantly green, plus color filtering media in the form of dyes to respectively control the passage of color components of light up to, within, or beyond respective strata, the respective color sensitized and afiected strata thereby providing for the production of images reproducing natural coloration directly and inconjunction with substractive analysis.

According to my process, I apply to the emulsion of the ordinary black and white monochromatic film a sensitizing solution which may, for the purpose of this disclosure, be considered a colloidal suspension in the form of dye particles in different sizes to provide Stratification, and which incorporates in a dispersion medium of alcohol and water color sensitizing and filtering dyes of the following nature and in the following proportion:

For the warmer colors pinacyanol or cyanine, relatively large particles in alcohol;

For the cold colors, pinachrom and Erythrosin in aqueous solution, and Orthochrom T in alcoholic solution, the particles being relatively of small size;

For color filtering, Rose Bengal medium size particles and Rapid Filter Yellow of fine particles, both in aqueous solution.

I prefer to use the above specified color sensitizing and filtering dyes in the following quan"- tities, with respect to the dispersing medium: I dissolve 1 g. of Pinorthol 1, which comprises essentially of a mixture of Pinachrom and Erythrosin and a slight amount of Rapid Filter Yellow, 1 g. of Rapid Filter Yellow and .4 g. of rose bengal, in order, in 150 c. c. of water; I then add to the above solution 25 c. c. of 1/1000 alcohol solution of Pinacyanol and 25 c. c. of 1/ 1000 alcohol solution of Orthochrom T, with stirring, after which I add 200 c. c. of alcohol, and then add water until the solution makes up to 500 c. c., with stirring.

In operation, I sensitize the film by spraying or coating the emulsion, which emulsion may be carried on glass, paper, or celluloid, as applied for different kinds of photography, or the sensitizing solution is sprayed or coated onto a carrier, in the nature of glass, water-proof paper, or celluloid, and a layer of emulsion then deposited thereon; in either case of which the sensitizing solution, that is, the respective constituents thereof, penetrate by diffusion, at rates dependent upon the particle size thereof, into the emulsion, to form three clearly defined strata, in the first of which, the product of the silver salt and the particles of the sensitizing solution reacting therewith provides for acceptance of the warmer colors, to wit: red and its derivatives; in. the next adjacent of which strata, the product of the silver salt and the particles of the sensitization solution reacting therewith provides for' the acceptance of the colder color to wit: green and its derivatives, and in the third stratum of which the product of the silver salt and the particles of the sensitizing solution reacting therewith provide for the acceptance of the-colder blue color and its derivatives. I

To more clearly define the result with respect to the constitution of the three-strata formation of the emulsion after sensitization, it should be noted that the first stratum contains a preponderance of the slowly diffusing Pinacyanol particles, a much smaller amount of the relatively larger and faster diffusing Pinachrom, erythrosin, Orthochrom T, and rose bengal particles, and a very small amount of the fine and swiftly diffusing Rapid Filter Yellow particles, andin such layer the silver salt is essentially and for all practical purposes completely sensitized for only the color red and its derivatives.

The next adjacent stratum contains a pre- The next adjacent or third stratum contains a preponderance of Rapid Filter Yellow comprising the fastest moving of all particles, and in such layer the silver salt, being normally predominantly sensitive toblue, becomes eflfective only to accept the blue component of light.

It is to be understood that the action or effect of rose bengal and Rapid Filter. Yellow, the

filter dyes, is not considered with relation to the color sensitization of the silver salts in the respective layers and the formation of color images by the reaction product' of the sensitizing dyes in the respective strata with such salts, but their action in the respective strata is directed in the subtractive analysis of light upon exposure of the sensitized film to a control for limiting the passage of blue and green components of light beyond the stratum in which such colors are accepted; as, for example, the blue component of light being accepted in the furthermost stratum, by virture of the presence in such stratum of the silver salt which normally is predominantly sensitive to blue, and which is unaffected by the color sensitizing solution, the Rapid Filter Yellow being minus blue in its characteristics or properties, prevents the passage of blue components into the middle of the green stratum, and'the uppermost or red stratum; rose bengal being minus green in its characteristics or properties limits the passage of green component to the intermediate or green sensitized stratum, and prevents the passage of the greenlight component into the uppermost or red sensitized stratum.

Although two methods of t sensitizing of the emulsion have been specified, I prefer, from the though the second method described has ad-- vantages, particularly in color photography involving a paper film, since it is coneededly advantageous to have a blue sensitivity in the entrant stratum, and red sensitivity in the emergent stratum.

Further, I have found it advantageous in the event of the two methods above described for sensitization as applied to pre-wet the emulsion, and for such purpose, I apply a borax solution, the function and application of which is more clearly defined in a co-pending application filed by Joseph S. Friedman August 3rd, 1934, Serial No. 738,214, and assigned to the Omnichrome Corporation, the assignee of this application. By

the use of such reagent for pre-wetting the emulsion, I am enabled to provide an emulsion whose silver salt content is constant,'but whose depth is increased several. times by the swelling of the gelatine dispersion medium carrying the silver salt in the emulsion, to provide for more thorough and complete difiusion of the respective color sensitizing and filter-dyes to the necessary depth.

It is to be understood that by the expression sensitizing solution is meant a solution in the nature of a colloidalsuspension, incorporating a dispersion medium carrying dyes of relatively different particle size, some of such dyes being capable of sensitizing silver salts in the emulsion of film by chemical reaction for diiferent color values, and others being adapted, upon dispersion within the film emulsion, to serve as color filter media; the sensitizing solution being so constituted upon application to emulsion as to provide diffusion of the dye particles therein, into the emulsion, to form a plurality of contiguous strata in the emulsion, in each of which the silver salt is acted upon or afi'ected so as to provide, upon exposure of the film, for the formation of images of its predetermined specific primary.

color and derivatives, to the exclusion of all others.

Although I have indicated a specific sensitization solution, I do not limit myself'to the use of this solution, or all of the ingredients thereof, together in the same proportion, it being within the province of this invention to vary the num-- her and type of dyes, and the particle size thereof, in the dispersion medium, so long as upon application of such sensitizing. solution to an emulsion of a mono-pack film, a multi-layer stratification, particularly a three-layer stratification of the type described, is produced in the manner described.

With respect to the dyes herein mentioned, following is the color index of each thereof as recognized and published under the Society of Dyers and Colourists Color Index: Pinacyanol,

No. 808, cyanine, No. 806, Orthochrome T, No.

807, erythrosine, No. 772, rose bengal, No. 777, Rapid Filter Yellow, No. 640.

It is obvious that various changes and modifications may be made-to the details of component applied and the process involved without departing from the general spirit of the invention 2. A method of treating a mono-pack film, comprising diffusing into the emulsion of the film a reagent, incorporating sensitizing dyes and filter dyes of such particle size and rate of diffusion for such time as to produce in the emulsion a plurality of strata predominantly sensitized respectively to record difierent color aspects, each stratum being affected'to exclude substantially the recordation of color aspects other than its own.

3. A method of treating a mono-pack film, comprising diffusing into the, emulsion of the film a reagent incorporating sensitizing dyes and filter dyes of such particle size and rate of diffusion for such time as to produce in the emulsion a three-strata formation, each stratum being predominantly sensitized to record different color aspects, each stratum being affected as to exclude substantially the recordation of color aspects other than its own.

4. A method of making a sensitized mono-pack film for use in color photography, comprising subjecting the emulsion thereof to the action at one time of a single reagent, incorporating colorsensitizing dyes and filter dyes of such particle size and rate of diffusion for such time as to produce a multi-strata formation in the emulsion the silver salts in each stratum being affected to record predominantly a specific spectral range,

and to be unaffected substantially as to the other .spectral ranges recorded in the other strata.

5. A method of making a sensitized mono-pack film for use in color photography, comprising subjecting the emusion thereof to the action at one time of a. single solution incorporating color sensitizing dyes and filter dyes of such particle size and rate of difiusion for such time as toproduce a three-strata formation in the emulsion, the silver salts in each stratum being afi'ected to .record predominantlya specific spectral range and to be unaffected substantially as to the other spectral ranges recorded in the other strata.

6. A method of sensitizing a mono-pack film for use in color photography, which comprises treating the emulsion of such film with a reagent incorporating color sensitizing dyes of such particle size and rate of diffusion for such time as fected as to exclude substantially the recordation of color aspects other than its own.

8. A method of sensitizing a mono-pack film for use in color photography, which comprises treating the emulsion of such film with a reagent incorporating color sensitizing dyes and filter dyes of such particle size and rate of diffusion for such time as to produce in the emulsion a multi-strata formation, each stratum being predominantly sensitized to record different color aspects, the top stratum being affected to record only the 'red aspect, the intermediate stratum being afi'ected to record only the green aspect, and the lower stratum being affected to record only the blue aspect.

9. A method of sensitizing a mono-pack film for use in color photography, which comprises treating the emulsion of such film with a reagent incorporating color sensitizing dyes and filter dyes of such particle size and rate of diffusion for such time as to produce in the emulsion a multi-strata formation, each stratum being predominantly sensitized to record different color aspects, the top stratum being affected to record sensitized.

only the red aspect, the intermediate stratum being affected to record only the green aspect, and the lower stratum being affected to record only the blue aspect, each stratum being affected as to exclude the recordation of color aspects other than that to which the silver salts have been 10. A method of making a sensitized monopack film for use in color photographyfcompris ing a silver halide emulsion upon a support, sub-' jecting the emulsion to a reagent containing color sensitizing dyes and filter dyes, the rate of diffusion of said dyes being controlled bythe particle size thereof, whereby a single treatment for a 

